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Solar panel testing and hotspots

Rooftop solar, once installed is often assumed to crank power without any attempt to test its efficiency as time elapses. Apart from the collection of debris on panels or some other obvious obstacle to proper operation. Other things to cause problems are a shadow cast from a new, neighboring construction.

There are tests that are readily performed and that provide clues as to what’s going on with the installation. Both panel failure and inverter failure or the occurrence of frequent high line voltage causing the inverter to switch off AC power production. The latter is a real issue that now affects the bulk of solar. Insiders in the electricity distribution business know about the troubles they go through trying to adjust on line tap changers—and somehow never getting it right. It has contractors reading up on inverter manuals to alter the settings so that power can still be pushed out at 254 volts, single phase.

What can cause damage to solar panels?

Leaves, dead birds and other small animal life caught between panels and the roof that can cause excessive local heating or cause excessive leakage current to earth. These can be eliminated before trouble starts. What is not realized is that panels do degrade over time—and that can be checked with a suitable insulation tester. The insulation test is between the negative and positive rails with respect to earth.

Thin panels are more subject to potential induced degradation than thick panels. The voltage across the cells with respect to the grounded frame causes a drift of sodium ions in the protective glass to damage the performance of cells. Atmospheric contaminants, such as chlorides (in marine environments) and sulfur dioxide and nitrous oxides (in industrial locations), are deposited on array structures. Once deposited, the contaminants react with oxygen and water and typically increase corrosion rates by releasing electrons from the metal’s surface. It is interesting to note that corrosion rates can be effectively decreased in areas of high rainfall, as contaminants are regularly washed away from the structural materials.

How should Insulation Testing be done?

The way the insulation testing is normally done is by shorting the positive and negative rails and doing one insulation measurement to earth. It is smart to first isolate the panels with the DC isolation switch. However, a better way to test the panels is to measure both the positive and negative rails separately.

The Hioki IR4053 https://www.hioki.com/file/cmw/hdTechnicalDataEn/50/attached_file/?action=browser&log=1&lang=en  is designed for solar panel testing; it will measure open circuit voltage, and can measure both rails for insulation strength to earth without having to short the positive and negative terminals. Another test to gauge panel performance is a short circuit test which will indicate problems such as photocell failure. The Hioki CM4376 )with Bluetooth that will allow you to easily get into tight spaces with their new innovative slimline jaw) will measure DC panel current as well operating voltage and can also be used on the inverter output to measure AC current and therefore power. https://www.hioki.com/en/products/detail/?product_key=6476-

Even Solar panels with good guarantees can break down.

Solar panels of good quality come with meaningful guaranties of performance and can be expected to perform efficiently over decades, but even so untimely failure of panels is always a distinct possibility. No matter the care taken during installation, microcracks in the glass surface of panels possibly caused during transport or during placement, can in due course, cause panel failure or at least, reduce panel efficiency sufficiently that reduction in power output is more than a few percentage points.

Some examples of the types of problems we are talking about

cracks in glass panel

 

Signs of a Hotspot

 

Cracks and Hotspots

 Bypass diode failures can cause Hot Spots

Hotspots in panels can develop through faults in manufacture, through opens in bypass diodes or some other reason but with the same effect, the avalanche breakdown of a cell (the photovoltaic cell is a current generator and a diode in parallel—normally not conducting, and reverse biased if the cell is shaded). In practice, testing bypass diodes is a bit of a pain. They are frequently encapsulated, therefore precluding tests but if accessible, then testing is possible, for example in ground installations.

Can you test Opens and Shorts on bypass diodes?

Yes you can. There are special purpose bypass diode testers that allow open and short tests in broad daylight . Yes no more night time testing! The Hioki FT4310 https://www.hioki.com/en/products/detail/?product_key=6415 is a special field test instrument for testing opens and shorts on bypass diodes. Panels can continue to operate more or less satisfactorily in terms of string current but if finally, an open occurs, the whole string is knocked out therefore causing a notable decline in inverter power output.

Although not frequently used for domestic installations, the I-V (current and voltage curve) tracer is ideal for testing panel performance as well as string tests. https://emona.com.au/products/electronic-compliance-testing/solar-pv-testing/solarlink-kit.html An actinometer measures the intensity of the sunlight, and a ‘sweeping panel load’ traces out the current-voltage curve of the panel. In some instruments this can be compared to standard panels by reference to panel model/type stored curves.

Testing instrumentation can be limited by using AC/DC clamp meters that have sufficient range to measure open circuit voltages and that have Hall-effect clamps suitable for DC current measurement. They therefore are well suited to measuring the operation of inverters as both DC power and AC power can be measured.

Improper operation of your Solar system is going to cost you more than just lost revenue off your power bills.

You can safely bet on the market for solar systems continuing to increase in demand and also that proper operation of domestic systems will be more and more important. Why? Because in due course—it’s already mooted by the Australian Energy Market Commission (AEMC) that domestic connections to the grid will have to pay a fee for the ‘privilege’ of being able to pump out power—and this is irrespective of whether solar systems are working properly or not.

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Practical Ways to Save Energy Bills in the Office

Data measurement – identify opportunities to save energy. Invest in a data logging service or try these simple things

There are many ways to save energy, most of which cost little to implement and realise savings. As with any process, it is useful to start by assessing where you are, your present consumption, the purpose is not to decide whether energy reduction is applicable, rather to set a benchmark; start by gathering some data and doing some very simply calculations.

Read your meters (electricity, gas, heating oil, petrol, diesel and water).

You may only get billed monthly or quarterly, so reading the meter every week preferably every day will give you a better breakdown of when the energy is used. Read the meter first thing in the morning, at lunch start and end and the end of the working day. How much are you using in the morning, lunch and afternoon and at night? Plot a graph using a spreadsheet, do this for a week or two at the most, compare Friday evening’s to Monday morning’s reading.

Benchmark – kWh per employee or kWh per m2.

For an office that does not produce a physical product, therefore has no manufacturing space a useful ratio is kWh per employee per annum, the total number of kWh used over the year, divided by the number of employees in the office. Be careful, the kWh/ employee figure can be deceptive, it assumes that all employees are equally efficient.

For this to work we need to be honest, here are the figures for a small Office for 2010:- 1,500 kWh per employee per annum (2010). 94kWh per m2 per annum (2010). 10kWh per widget per annum (2010).

Compare to your neighbours, competitors, partners.

 If you are a pink widget producer, it can be difficult to compare with other pink widget producers, I therefore suggest you compare with similar non-competitive industries, sometimes that can be as simple as your neighbouring industries, use the figures above, however you may both be open to discuss actual energy figures.

Education.

This is an easy step to take, ask staff to turn out lights when leaving an empty office, not to leave PCs on when going for an hour’s lunch, a 12% saving on its daily running cost, don’t leave them on at night either. Incentivise, make energy reduction and savings part of the bonus scheme. Turn lights, PC’s, radiators and heaters off when the room is vacant.

Lighting.

There are legal limits re. the amount of luminance needed in various work settings. Assess your needs, if you have too much light, remove some bulbs/tubes. Consider upgrading to higher efficiency units. Where and when possible, open the blinds, let the light in. Ensure you have no incandescent lamps in the building, upgrade halogen spotlights to low energy types or better LED.

Thermostatic control & HVAC.

Heating and cooling settings should not be adjusted by members of staff, only by those that are authorised. If certain staff want to be warmer or cooler, move them closer to, or further from heating and cooling. Ensure that HVAC is not on Saturdays and Sundays, this is common problem and of course, on one ever knows it is on, as no one is ever there. Ban the personal fan heater, they get left on, electricity is normally the most expensive form of heating.

Data measurement – identify opportunities to save energy

Invest in a data logger service.

We recommend the Electrocorder! The EC-2VA is designed for use in the office or home, it allows you to determine the actual energy profile of many items of equipment. For larger premises, perhaps with 3 phase electricity, a current logger is sufficient to tell you the rough energy usage over a week or so, this will let you compare the theoretical estimates to these actual results. A voltage ‘Duty Cycle’ logger will let you analyse a pump or fan run duty cycle, which in turn can tell you when an oil or gas heating system was on. Although the fan or pump energy usage may be fairly insignificant, the overall heating energy use (gas or oil) may be very significant,… does it run when the building is empty, is the frost protection set to 15C rather than 5C?

easy to use single phase current and voltage logger

Get in an expert to data log – capture your energy profile Calculate acceptable

Datapro Communications team of engineers and technicians can help you here contact them info@dataprocomms.com.au

3 phase current and voltage logger

Vending machines.

As long as there are no perishables in the machines, turn them off at night, put them on a 5/2 time-switch, on an hour before work starts, off an hour before work ends and off at the weekends. Toilets. Put the lights on an IR sensor, check hand dryer sensors are working correctly, and the timer is set, such that you can indeed dry your hands.

In the Kitchen.

Educate staff not to fill the kettle to the top, just according to what they need. Put coffee makers on a time-switch, so they are not left on at night. Get staff to co-ordinate their breaks, so one kettle boil does several people.

Set targets for reduction.

A good starting point is a 5% or 10% reduction target, perhaps to be achieved in 6 to 12 months, the sooner you implement the changes the sooner you start to save. Energy reduction make you more competitive and gives you the edge, any money saved can be devoted to product development, process improvement or advertising. Monitor your progress towards the targets. Use time-clocks and time-switches to enforce a ‘use-envelope’ of use for non-critical equipment.

Educate after hour cleaners to save.

If your cleaners enter your site at 05.00 and turn on all the lights, the HVAC, escalators, vending machines, they are spending a considerable amount of money on your behalf each year. Check up on them. Appoint a responsible person, to analyse and check all spending on energy. Put several members of staff in charge of checking vacant rooms are not lighted or heated.

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Using the EC-7VAR-RS Logger for Power Factor Measurement

Case Study: Thermoservice Ltd, Country – Bulgaria

Product used was EC-7VAR-RS

Using the EC-7VAR-RS for simple Power Factor measurement

“The software is user friendly with a lot of possibilities to interpret the recorded data that we require!”

Who are Thermoservice Ltd?

Thermoservice Ltd specialize in Field Services, Design and Building, Supply and Installation of all-weather facilities.

They have extensive experience in servicing of air conditioning equipment and other installations. The service staff use specialist tools and supplies for repair and maintenance of all types of air conditioning and refrigeration equipment.

Why  did  they need the EC-7VAR?

“The main reason to purchase the EC-7VAR was to undertake energy efficiency audits, and we needed a voltage and current data logger to record the data so that we can make decisions”

After using  the  EC-7VAR

The EC-7VAR performed better than I expected. The software is user friendly with a lot of possibilities to interpret the recorded data that we require!”

“It was simple and easy to connect for us to gather the Power Factor measurement data, easy to connect to a computer in order to download the data recorded.”

“When we conduct an audit, we are interested in Power Factor and the actions that we take depend on the level of reactive power. The EC-7VAR worked well. I would gladly recommend it for this application “

Purchasing experience “We found the product on the internet. and bought it   on -line”

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Over Pressure Electrical Regulators Saves You Money

Wasting electricity is like wasting water

Leaving a tap on needlessly wastes water and costs you more money than you need to pay—that is common sense. Something else that is also common sense is needlessly wasting electricity—except many people think because it relates to electricity—it’s either too difficult to understand or probably just ‘bull’.

A direct equivalent water tap, electricity switch.

There’s a direct equivalent to a tap—a switch—and there’s something else, water pressure which is equivalent to voltage. You can save electricity by switching off stuff that is not needed to operate, but what about gear that needs to stay switched on? Back to the water example: the tap is on for the garden hose, and water pressure has gone up. More water flows and your water bill get’s a little kick along. Not only that—you may be overwatering your plants and shortening their life.

Voltage is equivalent to water pressure.

 As already mentioned, voltage is equivalent to water pressure and the water volume measured in an hour is equivalent to your electricity usage in an hour. Now, electrical pressure, voltage, is measured in volts—who would have thought. Your electricity retailer delivers the electrical equivalent of water—its whatever flows into your bucket—so to speak—you get charged for. What about the electrical pressure?

You pay more if your electrical pressure goes up.

We now understand that more pressure delivers more water and you pay more if the electrical pressure goes up above what your plugged-in appliances require—somewhat like overwatering because it can also shorten the life of your appliances.

Australian Standard AS60038 equates the electrical pressure (Voltage) to be 230V.

In 2000, Standards Australia issued a system Standard, AS60038, with 230V as the nominal voltage with a +10% to –6% variation at the point of supply. Most appliances and equipment items coming into the country are likely to be 230V rated, as they have been designed to IEC Standards that are 230V based. This means the optimum performance, lowest cost to operate and life expectancy of the appliance will be when it is subject to a maximum electrical pressure (Voltage) of 230V.

Electricity retailers have no control over your Voltage pressure.

Electricity retailers have no control over voltage—it is whatever the poles and wire people provide—they are the equivalent to the Shire that owns water pipes. In most cases managing this excess pressure (over Voltage) comes down to what you do as the owner. There is no commercial gain for the Retailers to address this. In fact, if they do, they will lose significant revenues—so why would they  

Now the magic of electricity is uncovered what does the extra electrical pressure (Over Voltage) do to my purse?

Let’s take an example. Let’s say in your area electricity is usually delivered at 235 volts but on some days, voltage goes up to 255 volts, Question: how much do you think you have to cough up for this extra electrical pressure? The ratio of 255 divided by 235 is 108%. Not that bad! Well, usually for things like pool pumps, fridges, stoves, lighting, stuff on standby like your TV, the increase is the ‘square of the ratio’ or 1.0805 multiplied by 1.0805, or a whopping 18% (rounded) extra Ouch!

Save Money—How!

But what happens when we control the electrical pressure to no more than 220Volts so that it doesn’t matter what’s happening out on the grid, everything in your control is working at 220Volts. Well its simple YOU SAVE MONEY! Using the maths above the ratio of 220 divided by 255 is 0.8627. Likewise, the savings is also ‘square of the ratio’ or 0.8627 multiplied by 0.8627 gives you a whopping saving of 26%.

A word of caution.

Voltage is variable and as we have learnt various influences both internal and external can affect how high or low it rises or drops—so the savings can be better or lower than shown. However, what the maths does show us is if you control the electrical pressure (Voltage), you can save money because in most places around Australia the phase to neutral voltages are consistently in the higher band of the allowable Voltage Standard—especially in Country areas and in places where there is a high take up of Roof Top Solar systems.   

FactYou pay more over a year than you really needed to if the electrical pressure (Voltage) in your area often goes high.

You’re a busy person—you have better things to do than to watch the electricity meter. You more or less trust that you’re not getting more electricity delivered during the day than your household needs—but The fact is  you pay more over a year than you really needed to if the voltage in your area often goes high.

Put in a PV Solar systemthat will fix it, won’t it?

If you have a solar panel setup and you are relying on selling some electricity back to retailer, then this extra electrical pressure may very well stop your solar system from working while voltage is high. Wow!! How is that?

Roof mounter Solar systems are like mini water towers and need the extra pressure to push a flow against the mainstream.

Your roof mounted solar panels are like a mini-water tower. They push out the equivalent of water and therefore have to have a wee bit more pressure to get the water to flow ‘against the main stream. OK now we are in the territory of electricity 101. The poles and wire folk are obliged by the Minister to keep electrical pressure within a tight range. In truth, many struggle with this but the easiest fix is to stop your solar system. You are perhaps in the dark about this but inside the inverter mounted on a wall of your house is a voltage monitor and switch which switches off the inverter when the pressure goes high!! In some areas during sunny days inverters are as much on as they are off. Ouch!! Guess what, here’s where the ‘bull’ comes in, and you’ll hear comments along the line of ‘ah nothing to worry about—doesn’t happen here—BUT IT HAPPENS IN LOTS OF PLACES.

There is a ‘FIX” solution—Put in an electrical pressure (Voltage) controller.

Just like a water pressure reducing valve if you have an over electrical pressure (Over Voltage) situation in your installation you can put in a Voltage Controller system. The payback can be calculated not just on the savings of the lower kWh consumption but also the impact of keeping the roof mounted solar system working continually. If you wanted to add an extra value on the benefit of improving the longevity of your electrical equipment and appliances, then this will only help the payback.

Energy Logging the first step to identifying where savings can be found.

A power quality logger will generally be needed to sort out voltage problems or to check compliance with the new 230V Standard. A Class A power-quality logger will be required to ensure compliance with AS 61000.3.100 power quality standard, if the supply is suspect, and it will need to be installed for at least one week. Class B instruments are great for locating faults but while you’re logging a site you may as well understand the whole electrical profile of the site for a just a few extra ‘bikkies’. Datapro Communications can help you in this area. Working alongside your preferred electrician we can help identify where your issues are, what you need to do to save money and improve electrical efficiency and what the payback will be. Contact us at info@dataprocomms.com.au

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Why monitoring voltage, power, power factor and vars is important to understand where and how you can save on electricity bills:

Monitoring and logging voltage, power, power factor and vars essential in network fringe areas. Let’s look at one aspect – that of Solar PV Inverter Installations to see why this is important?

  1. Solar PV inverters particularly in remote areas are susceptible to being switched off due to excessive voltage rise or fall. This is part of the design and protection mechanism for the inverter and requirements from the network operators to avoid excessively high voltages been put into their grid. Excessive voltage rise will most likely occur when the sun shines brightly, and the temperature is at its highest (known as high insolation) and electrical energy usage in the home is low because the occupants of the house have gone to work.
  2. Because of this it is good practice to monitor Solar PV installations for voltage regulation to 254 volts single phase and low voltage down to 207 volts to see what’s happening on your installation. Solar PV installations will switch off when these high or low voltage values occur. This means you are not generating electricity for internal usage, selling back to the grid or charging your batteries if you have battery storage installed.
  3. In remote areas especially the distribution grid is considered weak (low reactance to resistance (X/R) ratios), because the power generation stations are located far away from the consumption points. Therefore, significant penetration of solar PV installations as we see happening can cause voltage issues such as voltage rise and dip. In certain parts of country Victoria, the switching off Solar PV installations happens continually.
  4. In addition to monitoring voltage levels it is also good practice to monitor Power factor and vars as Solar PV installations are sometimes required to provide network support by way of vars injection. Both high voltage and the injection of vars into the grid affect the efficiency of the inverters and therefore slow down the cost recovery of your Solar PV installation. High voltage will shut down the inverter and vars injection lowers the useful power output, resulting in loss of feed-in recovery and/or reduced battery charging if you have them installed. High line voltage can cause an inverter to suffer relay chatter with eventual breakdown of the PV Inverter and manufacturers coping the cost of repairs or replacements, not to mention a bad name.
  5. High voltage in your installation equates to higher electricity bills. This is a fundamental principle of Ohms Law. Power (Watts) equals Amps (I) times Voltage (V) P = I x V. If you are drawing 20Amps at 254V you are using 5.08kW of power. Our electricity bills have a component that charges against kW/hr usage. However, if you are controlling your voltage at 230V you are using 4.6kW of power a saving of 21.95% (Voltage ratio’s squared) on your electricity bill. Control your voltage at 220V then you are saving 33.3% of your electricity bill. The irony of this is you could be having higher electricity bills now, even though you have a Solar PV installation fitted. How is this possible? Experience has shown us that in remote areas the Voltage can rise as high as 275V for long periods typically where no auto transformer tap changing exists. This means your Solar PV inverter installation has switched off and your installation is being subjected to high voltages from the grid. Using the formula above, 20 Amps times 275 Volts equals 5.5kW which equates to a 42.9% higher electricity bill. The moral of this story is you have to control your voltage levels. Trust me no one else is going to do this for you as there is no commercial interest in them doing this for you.
  6. Low power factor in your installation also equates to higher electricity bills. Typically, not an issue in domestic installations but can certainly be a big issue in Commercial installations such as a McDonalds Restaurant and Industrial installations if not corrected. A component in our electricity bills called Demand Charges penalizes us for wasting good usable power supplied by the network operators by not addressing our low power factor problem. 

Our experience shows the Acksen power loggers are simple to use and ideal for measuring and recording the power output of;

  1.  Solar PV inverters.
  2. Neutral to Earth voltage monitoring especially in areas where earth resistivity is high because of the use of plastic water pipes. A broken neutral can cause dangerous touch potentials.
  3. Neutral Current monitoring is important where Solar PV installations causes unequal power distribution in the phases

Acksen makes the task of monitoring more efficient by providing combination models, which measure voltage, current, power and power factor in one unit.

When the Acksen loggers have finished recording they can be directly downloaded to PCs using (free supplied) Electrosoft software allowing the data to be viewed immediately on-screen and to be saved or exported for later analysis.

Datapro Communications now located in the Echuca Moama border towns has extensive knowledge in Power Logging and Power Quality Analysis and can provide the report  and recommendations on what to do to control Voltage and other electrical parameters effecting your installation and pushing up your electricity bills. For more information please email  info@dataprocomms.com.au or go online www.dataprocomms.com.au for equipment sales or hiring.

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Data measurement – identify opportunities to save energy

The term Energy Audit is now common currency, with most understanding what it means but perhaps not knowing and how to perform one; the aim of this document is to explain an ‘Electricity Energy Audit’ using the Acksen Electrocorder range of data loggers. The ultimate aim of an Energy Audit should be to reduce usage.

Ongoing data logging identifies issues with Supply and Equipment

Calculate the monetary value of future energy savings. Low cost investment for long term energy savings

The first thing in any energy audit is to look at the information or data that you already have to hand, this usually takes the form of utility bills, invoices and meter readings, this can tell you a lot historically, what it will not tell you is where the energy went, which equipment,  circuits, buildings or divisions consumed the energy and when. To answer these questions you have to record data over a period of time. To do this you will need an Electrocorder.

Before you log data you’ll need to know the electrical layout of the system or premises to be audited, ask an electrician to explain the wiring diagram for the premises, if you don’t have one, perhaps you’ll need to create one. The diagram will show you the various circuits and connections of your system, in turn this may help you to determine the best logging points and where to get access for recording.

Our free Electrosoft soft ware which is supplied with every logger allows you to input the systems voltage, for current only loggers, thus it will work out the power consumption over the logging period, assuming that constant voltage

So are you a Pragmatist or a Purist:

There is no need to be a purist; to correctly measure power and energy you need to measure voltage, current, power factor and time however for many situations measuring only current will do! The voltage you receive from your utility is not constant, generally you have no control over it, those variations will be fairly cyclic over the period of a day or even a week, so in essence voltage can be treated as a ‘constant’ there is therefore no need to record it. For the purposes of a comparative test or audit (before and after) you can robustly use only current.  This makes life a lot easier for logging, no direct connection to voltage terminals, simply clip the CT’s or Rogowski Coils around the conductors and press the start button to record.

Download the full application note and see how easy it is to identify opportunities to save energy https://www.electrocorder.com/Portals/0/downloads/documents/app-notes/AN-Energy-Audit-En.pdf